http2: confusion with how aborted ClientHttp2Stream is reported

[santigimeno]

Take this sample code:

const h2 = require('http2');

const server = h2.createServer();
server.on('stream', (stream) => {
  stream.session.destroy();
});

server.listen(0, () => {
  const client = h2.connect(`http://localhost:${server.address().port}`);

  client.on('close', () => {
    server.close();;
  });

  const clientStream = client.request();
  clientStream.on('aborted', () => {
    // Never called
    console.log('aborted');
  });

  clientStream.on('close', () => {
    // `rstCode === 8 (NGHTTP2_CANCEL) 
    console.log('close', clientStream.rstCode);
  });
  
  clientStream.on('error', (err) => {
    // Never called
    throw err;
  });
});

in which clientStream is aborted before any response is generated via the stream.session.destroy() call. I would expect in this case clientStream to emit an error, but by looking at the code, this specific case is explicitly not reporting the error because:

// RST code 8 not emitted as an error as its used by clients to signify
// abort and is already covered by aborted event, also allows more
// seamless compatibility with http1

but, as demonstrated in the example, the aborted event is not reported. I don't know exactly what the http1 compatibility means in this context.

Also, if we look at the documentation of the Http2Stream close event, it seems to contradict the following statement:

The HTTP/2 error code used when closing the stream can be retrieved using the http2stream.rstCode property. If the code is any value other than NGHTTP2_NO_ERROR (0), an 'error' event will have also been emitted.

Any thoughts whether this is a bug in the code, the documentation, both?.

Thanks!

[RafaelGSS]

cc: @nodejs/http2

IMO, this seems to be a bug in the code, but it might be a workaround instead due to the number of tests that break if we revert that operation. I'd defer the suggestion to @mcollina @jasnell @addaleax, but in case of no response, I'd try to emit a stream error in that scenario.